1. Field of the Invention
The invention relates to a liquid crystal display device, and in particular to a liquid crystal display device that is constructed through a fabrication process to apply a sealant to either or both of two liquid crystal medium sandwiching substrates for laminating those two substrates through a given gap, and for adhering to and sealing them, and then to actually laminate the substrates.
2. Description of Related Art
In a fabrication process for liquid crystal display panels, a sealant consisting of a material such as thermosetting resin paste is used as a material for bonding two panel substrates and for forming a chamber cell into which a liquid crystal material is sealed between the substrates. In general, a picture frame-like pattern of the sealant is printed so as to be located along the fringe of one of the substrates (in other words, so as to surround a display area keeping a given space to the display area). Then, this pattern-formed sealant, after some predetermined processes, is pressed against the other substrate and cured through a heating treatment so that a given gap (liquid crystal cell gap) is formed between the substrates in a substrate alignment process.
However, in these processes, there is a possibility of the sealant leaking or flowing into the display area because the sealant is pressed against the substrate in the substrate alignment process and the sealant may be liquefied or softened in the heating treatment. If the sealant flows into the display area, pixel-forming elements including a color filter arranged correspondingly to the display area and pixel electrodes connected to TFTs might be covered with such flowing sealant or the quality of such elements might be deteriorated, which may further result in the so-called dot defect of the displayed image.
One of the conventional countermeasures against such encroachment of the sealant into the display area has been to provide a much sufficient distance between the pattern-formed sealant and the display area.
However, because of the recent tendency to expand the display area, a (market) requirement that a distance between the sealant and the display area should be shortened (the so-called narrow frame form) has been getting more and more strong, and therefore it cannot be allowed anymore to disregard the aforementioned problem of the sealant leakage into the sealant. Thus, it is a pressing need to provide a technique for preventing the leakage of the sealant into the display area when the substrates are combined even if the sealant has been put on closely to the display area.
From the aforementioned viewpoints, it is an object of the invention to provide a liquid crystal display device in which the leakage of the sealant into the display area can be very surely prevented.
In order to accomplish the object, a liquid crystal display device of one aspect according to the invention is a liquid crystal display device comprising: two substrates in which a display area is defined and which are overlaid with each other; at least two dam pattern structures being provided on at least one of the substrates or provided separately on both of the substrates, which have a pattern of surrounding the display area; and a sealant applied to the outside of the dam pattern structures in such a manner that the sealant surrounds the dam pattern structures, wherein the outer dam pattern structure adjacent to the sealant has a plurality of slits (for causing the sealant to pass therethrough).
According to this aspect, the slits or gaps of the outer dam pattern structure cause the sealant to easily pass through a passage and a space between the inner dam pattern structure and the outer dam pattern structure when the substrates are combined and adhere to each other. So, it is possible to suppress leaking out of the sealant into the display area beyond the inner dam pattern structure, that would be caused for some reason.
In the above mentioned aspect, any inner dam pattern structure of the dam pattern structures except for the outer dam pattern structure may have a pattern of surrounding the display area in a generally continuous form.
Any inner dam pattern structure of the dam pattern structures except for the outer dam pattern structure may have a plurality of slits for causing the sealant to pass therethough.
In the above mentioned aspect, the dam pattern structures may consist of three dam pattern structures, and the innermost dam pattern structure thereof may have a pattern of surrounding the display area in a generally continuous form.
Then the dam pattern structures may consist of three dam pattern structures, and the central dam pattern structure thereof may have a pattern of surrounding the display area in a generally continuous form.
In order to achieve the above mentioned object, another aspect of liquid crystal display device according to the present invention is a liquid crystal display device comprising: two substrates in which a display area is defined and which are overlaid with each other; one or more dam pattern structures being provided on at least one of the substrates or provided separately on both of the substrates, which have a pattern of surrounding the display area; and a sealant applied to the outside of the dam pattern structures in a form of surrounding the dam pattern structures, wherein said one or more dam pattern structures comprise a dam pattern structure of column-shaped section having a cross-section connecting between mutually opposite faces of one and another of the substrates.
Accordingly, the column-shaped section dam pattern structure completely prevent the sealant from coming into the display area, so that the problems previous mentioned can be overcome. Furthermore, this aspect has an advantage that the column-shaped section dam pattern structure can determine a distance between the substrates at a fringe section of the substrates, whereby it will be useful for control/setting of a thickness of the liquid crystal cell.
In this aspect, the dam pattern structure of column-shaped section may have a pattern of surrounding the display area in a generally continuous form.
The one or more dam pattern structures may comprise: an inner dam pattern structure of column-shaped section having a cross-section connecting between mutually opposite faces of one and another of the substrates and having a pattern of surrounding the display area in a generally continuous form; and an outer dam pattern structure having a plurality of slits (for causing the sealant to pass therethrough) and being located on a side close to the sealant.
Here, the outer dam pattern structure may have a column-shaped cross-section connecting between mutually opposite faces of one and another of the substrates.
Furthermore, the one or more dam pattern structures may comprise: an inner dam pattern structure of column-shaped section having a cross-section connecting between mutually opposite faces of one and another of the substrates and having a plurality of slits; and an outer dam pattern structure of column-shaped section having a cross-section connecting between mutually opposite faces of one and another of the substrates, having a plurality of slits (for causing the sealant to pass therethrough) and being located on a side close to the sealant.
Preferably, intervals between the slits of the inner dam pattern structure of column-shaped section are longer than those between the slits of the outer dam pattern structure of column-shaped section, and the slits of the inner dam pattern structure of column-shaped section do not correspond to the slits of the outer dam pattern structure of column-shaped section.